You most likeky need to install the RTL8187b driver. Have a look at the aircrack-ng website and you'll see a link to an excellent driver there.
Another option is using what you already have in BT3 - airdriver-ng. Use it to check your both your installed and loaded drivers. Airdriver-ng can also retrieve, patch, compile, install, and load the driver.
Study up first, so that you don't break your system...and good luck.